The reciprocating internal-combustion engine of the two-cycle type is universally recognized as the simplest engine of those at present available. This has led to its almost universal adoption in the field of propulsion designed for small vehicles consisting of motorbikes and scooters with piston displacement between 50 cc and 125 cc in addition to so-called quadricycles with engine and a whole series of small tools and devices such as generating sets, chain saws, lawnmowers, outboard engines for aquatic use et cetera. The need for adoption of propulsion systems with ‘simple’ construction layout is required by the fact that they are low-value-added articles and therefore the industrial cost of propulsion systems as well as of the other components must be kept as low as possible. Other influencing factors are low weight (high power/weight ratio) and the limited maintenance they need.